Summary

Congenital high airway obstruction syndrome (CHAOS) is a rare but life-threatening condition that results from the obstruction
of the upper airways.

We describe a female newborn, from a Grávida II, Para 0, 36-year-old woman, with a routine ultrasound at 30 weeks’ gestation
that showed polyhydramnios. She delivered a live-born female baby at 36 weeks without any dismorphic features but with respiratory
distress. Attempts at endotracheal intubation were unsuccessful due to the presence of a mass obstructing the larynx. The
reanimation process was stopped after 20 minutes. Post-mortem examination demonstrated the presence of a total occlusion of
the larynx by a laryngomucocoele. Laryngocele, a congenital cyst of the larynx, occurs rarely and hardly ever as a cause of
CHAOS. What is more, laryngomucocoele has not been previously reported as a cause of CHAOS. These conditions represent a neonatal
emergency with reserved prognosis unless diagnosed antenatally allowing for a programmed ex utero intrapartum treatment (EXIT)
by performing tracheostomy while maintaining the placental circulation.